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Allan Hills A77155
Basic information Name: Allan Hills A77155
     This is an OFFICIAL meteorite name.
Abbreviation: ALHA77155
This meteorite may also be called Allan Hills 77155 (ALH 77155) in publications.

Observed fall: No
Year found: 1977 or 1978
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 305 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 2(1)  (1979)  L6
Meteoritical Bulletin:  MB 76  (1994)  L6
NHM Catalogue:  5th Edition  (2000)  L6
NIPR Catalogue:  2000 Edition  (2000)  L6
MetBase:  v. 7.1  (2006)  L6
Recommended:  L6    [explanation]

This is 1 of 10989 approved meteorites (plus 6 unapproved names) classified as L6.   [show all]
Search for other: L chondrites, L chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Writeuphelp
Writeup from AMN 2(1):
This text was reprinted from AMN 2(1) in AMN 4(1). In some cases, it may be an updated version from the original.

Sample No.: ALHA77155

Location: Allan Hills

Field No.: Y78010307

Weight (gms): 305.3

Meteorite Type: L6 Chondrite

 

Physical Description:

This sample is very rough on the exterior. The knob-like surface relief features are weathered orangish-brown on their tops and commonly reveal more less-weathered (light gray) material on their sides. No fractures were noted. The patch of black fusion crust (.5x2 cm) is preserved on the B surface. The stone is 9.0x4.5x4.5 cm and is rounded on the edges. The E surface is slightly more angular than the other surfaces, possibly representing a fracture surface. When the meteorite was cleaved, a non-weathered interior was exposed. A few halos of iron-oxidation were observed around light colored inclusions. A small area of darker gray material is present close to the N side of the sample on both the E and W butt-ends.

 

Petrographic Description: Brian Mason

In thin section chondrules are sparse and tend to merge with the granular groundmass; chondrule types include porphyritic and barred olivine with interstitial devitrified glass, and fine-grained pyroxene. Plagioclase is present in minor amounts, as anhedral untwinned grains. Accessory whitlockite was identified with the microprobe. Opaque minerals include minor amounts of nickel-iron and troilite, and accessory chromite. Limonitic staining is prominent around the nickel-iron grains. Microprobe analyses gave the following mineral compositions: olivine, Fa24; orthopyroxene, Fs20; plagioclase, An10.

Data from:
  MB76
  Table 2
  Line 122:
Origin or pseudonym:Main icefield
Mass (g):305.3
Class:L6
Weathering grade:A/B
Fayalite (mol%):24
Ferrosilite (mol%):20
Comments:26Al=71±3; NTL=25.4±0.1
Catalogs:
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References: Published in Antarctic Meteorite Newsletter 2(1) (1979), JSC, Houston
Published in Meteoritical Bulletin, no. 76, Meteoritics 29, 100-143 (1994)
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Geography:

Antarctica
Coordinates:
     Catalogue of Meteorites:   (76° 43'S, 159° 40'E)
     Recommended::   (76° 43'S, 159° 40'E)

Statistics:
     This is 1 of 39173 approved meteorites from Antarctica (plus 5051 unapproved names)
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